Thermoshaping machine

ABSTRACT

A shaping machine has upper and lower shaping tools movable vertically between an open position spaced apart and spacedly flanking a shapable strip passing between them in a generally horizontal travel direction and a closed position gripping the strip and also movable horizontally parallel to the strip between an upstream tool position and a downstream tool position. Upper and lower clamp plates offset horizontally from the shaping tools are also movable vertically between an open and closed positions and movable horizontally between upstream position and downstream clamp positions. Respective drives connected to the tools and plates alternately move the tools and the plates between their open and closed positions. This drive also move the tools and plates downstream in the direction substantially only when in the respective closed positions and moves the tools and plates upstream in the direction substantially only when in the respective open positions.

FIELD OF THE INVENTION

The present invention relates to a thermoshaping machine. Moreparticularly this invention concerns such a machine that is used in, forexample, the pharmceutical industry to make a package strip holdingpills, capsules, dragees, or the like, and to a method of operating themachine.

BACKGROUND OF THE INVENTION

A standard strip used, for example, to package pills is made by passinga flat thermoplastic strip between a pair of shaping tools, one of whichis formed with bumps that fit into complementary recesses on the other.In a standard operation the strip is passed through a heating stationjust upstream of the shaping tools so that when the strip is engaged bythe tools, which are usually cooled, it is soft and can easily beplastically deformed to have the blisters that are subsequently used tohold the product being packaged, e.g. pills. Downstream of the shapingmachine the blisters formed in the by-then-cool strip are filled withthe mall objects to be packaged, another film or a foil is bonded to thetop face of the blister strip to encapsulate the objects, and the stripis cut into pieces each having at least one blister and the encapsulatedobject.

Thus the shaping machine has an upper shaping tool and a lower shapingtool between which the strip is guided and which are movable relative toone another between an open position and a closed position, and a feederfor the strip. Because of the nature of this production operation it iscritical that the strip be conveyed continuously, that is at a constantspeed, through the various, stations and machines. This is particularlyhard to adapt to the actual blister-forming machine that must open andclose on the strip.

OBJECTS OF THE INVENTION

It is therefore an object of the present invention to provide animproved thermoshaping machine.

Another object is the provision of such an improved thermoshapingmachine that overcomes the above-given disadvantages, in particular thatoptimizes the cooperation of the continuously framing strip with thecycled operation of the thermoshaping machine.

SUMMARY OF THE INVENTION

A shaping machine has according to the invention upper and lower shapingtools movable vertically between an open position spaced apart andspacedly flanking a shapable strip passing between them in a generallyhorizontal travel direction and a closed position gripping the strip andalso movable horizontally parallel to the strip between an upstream toolposition and a downstream tool position. Upper and lower clamp platesoffset horizontally from the shaping tools are also movable verticallybetween an open position spaced apart and spacedly flanking the stripand a closed position gripping the strip and also movable horizontallyparallel to the strip between an upstream clamp position and adownstream clamp position. Respective drives connected to the tools andplates alternately move the tools and the plates between their open andclosed positions. This drive also move the tools and plates downstreamin the direction substantially only when in the respective closedpositions and moves the, tools and plates upstream in the directionsubstantially only when in the respective open positions.

With this thermoshaping machine for a continuously running strip, thelower shaping tool and the upper shaping tool for the shaping processmove along with the strip between the upstream end position and thedownstream end position in order to perform the shaping process as soonas the required synchronism is achieved between the upper shaping tooland the lower shaping tool and the strip.

Within the scope of the invention it is particularly preferred when theshaping tools and the feeder are operated alternately, that movedalternately between the closed and open positions during displacement inthe direction of travel of the strip in order to produce a continuousadvancement of the strip, i.e. the feeder itself need not be permanentlyactive, since part of the time workpiece advance is effected by theshaping tools. In this manner the synchronism is forcedly maintained. Inaddition, this ensures that the clamping plates may be easily movedbetween the downstream and the upstream end positions, that is thepositions where they switch travel direction, without interfering withadvance of the strip or causing unacceptable fluctuations in the webtension.

In the thermoshaping machine according to the invention it isparticularly advantageous when the distance between the downstream endposition and the upstream end position for the shaping tools and for theclamping plates in each case is greater than the travel of the shapingtools and clamping plates, and includes a synchronization zone forsynchronizing with the strip before the change to the closed position.As a result of this design it is not necessary for the clamping platesand the shaping tools to be completely up to speed when they start theirdisplacement between the upstream end position and the downstream endposition; rather, there is always an zone in which the shaping tools andthe clamping plates are synchronized with the strip. Thus the tools andplates have a chance to accelerate up to the web-travel speed as theymove out of the respective upstream and positions and only close whenthey are up to speed; similarly they disengage from the strip workpieceand have time to decelerate to a stop as they move into the downstreamend positions. Such operation makes it possible to move the fairlymassive shaping tools and clamping plates without using powerful drive,and greatly reduces shock and wear of the system.

When the shaping tools and/or clamping plates are in the closedpositions, that is locked with the blisters formed in the strip, it isalso advantageous when the distance between the reversal positionsincludes a deceleration zone after the interlock is released during thechange to the open position. This ensures that, for example, after thestrip is shaped and the blisters are formed the bumps provided for thispurpose in the upper shaping tool may be completely removed from theforced blisters before the upper shaping tool, and synchronouslytherewith the lower shaping tool, again loses the synchronism with theadvancement of the strip.

It is also within the scope of the invention that the displacement pathof the shaping tools between the upstream end position and thedownstream end position is smaller than the extension of the shapingtools in the direction of travel of the strip. The thermoshaping machineaccording to the invention may have a particularly compact design, sinceit is not necessary for either the shaping tools or the clamping platesto be moved between the upstream and the downstream end positions by afull length of the strip processed in a working cycle. This is becauseeven during the return between the downstream end position and theupstream end position the advance contributes to the change of the stripsection located between the shaping tools.

To improve the quality of the blisters formed in the strip, it is withinthe scope of the invention that at least one of the shaping tools istemperature-controlled, in particular thermally connected to a coolingdevice, in order to quickly cool the blisters formed by the shapingtools to below the shaping temperature of the strip, thus stabilizingthe formed blisters. It is advantageous when in addition at least one ofthe clamping plates is similarly temperature-controlled, in particularthermally connected to a cooling device. In this manner the strip maycontinue to be cooled, even when as the result of its continuous motionthe strip itself is no longer gripped by the shaping tools.

To allow the greatest possible flexibility in use of the thermoshapingmachine even during a format change, a controlled drive is provided ineach case for displacing the shaping tools and the clamping plates inthe feed direction. For this reason a hydraulically actuated, preferablypneumatic drive is provided for the clamping plates, likewise for thechange between the open position and the closed position.

It is also advantageous when the plane of the strip in the thermoshapingmachine and the shaping tools and clamping plates aligned parallelthereto define an angle of inclination with respect to the vertical.

BRIEF DESCRIPTION OF THE DRAWING

The above and other objects, features, and advantages will become morereadily apparent from the following description, reference being made tothe accompanying drawing in which:

FIG. 1 schematically shows a thermoshaping machine according to theinvention in a side view, with the shaping tools at the upstream endposition and in the open position and the clamping plates in the closedposition;

FIG. 2 shows the shaping tools during the acceleration synchronizationzone;

FIG. 3 shows the shaping tools in the closed position after the end ofthe acceleration synchronization zone and the clamping plates likewisestill in the closed position;

FIG. 4 shows the shaping tools in the closed position and the clampingplates in the open position;

FIG. 5 shows the shaping tools in the closed position and the clampingplates in the open position during the return from the downstream endposition to the upstream end position;

PIG. 6 shows the shaping tools in the closed position and the clampingplates in the open position at the upstream end position;

FIG. 7 shows the shaping tools and the clamping plates in the closedposition;

FIG. 8 shows an illustration corresponding to FIG. 1, with the shapingtools in the open position in the deceleration zone and the clampingplates in the closed position; and

FIG. 9 shows the shaping tools in the open position at the downstreamend position and the clamping plates in the closed position aftercompletion of their acceleration up to travel speed.

SPECIFIC DESCRIPTION

As seen in FIG. 1 a thermoshaping machine 1 for a strip W is conveyedfrom a supply roll through a heating station 17 in order to heat thestrip W to a shaping temperature and to shape the strip W in thethermoshaping machine 1 located downstream from the heating station inthe direction of travel 11 of the strip W. For this shaping thethermoshaping machine 1 has an upper shaping tool 2 and a lower shapingtool 3 between which the strip W is guided. The lower shaping tool 3 andthe upper shaping tool 2 are movable relative to one another by atpneumatic actuator 12 between an open position (FIGS. 1, 2, and 9) and aclosed position (FIGS. 2 and 3, 4, 5, 6, and 7). In the closed positionblisters B are molded in the strip W, generally by bumps provided in theupper shaping tool 2 which penetrate the strip W, supported by the lowershaping tool 3 that has cavities for accommodating the bumps.

In the thermoshaping machine 1 it is necessary to move the strip Wconveyed from the heating station 17 to the subsequent station in thethermoforming machine. For this purpose a feeder 4 which is alsoassociated with the thermoshaping machine has an upper clamping plate 5and a lower clamping plate 6 which are movable relative to one anotherbetween an open position (FIGS. 4, 5, and 6) and a closed position(FIGS. 1 2 and 3, 4, 7, 8, and 9) by another pneumatic actuator 13. Inthis respect the clamping plates 5 and 6 may be displaced in the sanemanner as the shaping tools 2 and 3.

The thermoshaping machine 1 according to the invention provides forspecial coordination between the shaping tools 2 and 3 and the clampingplates 5 and 6 that can be moved in a precisely coordinated mannerbetween respective upstream end positions 7 and 8 and downstream endpositions 9 and 10 parallel to the direction of travel 11 of the stripW, thereby continuously advancing the strip W at a constant speed withan alternating operation in the closed position during displacement inthe direction of travel 11 of the strip W. The tools 2 and 3 and theplates 5 and 6 have a length L₁ in the direction 11 that issubstantially longer than a length L₂ in the direction 11 through whichthey travel between their upstream and positions 7 and 8 and downstreamend positions 9 and 10 to ensure proper gripping, shaping and cooling ofall of the strip.

This dimensioning also makes possible an acceleration synchronizationzone for synchronizing with the tools 2 and 3 and the plates 5 and 6with strip W before the change to the closed position. There is also adeceleration zone in the change to the open position and completestopping of the tools 2 and 3 and plates 5 and 6. The tools 2 and 3 areshifted in the direction 11 by a variable-speed servomotor drive 14 andthe plates 5 and 6 by another drive 15.

Lastly, it is noted that at least one of the shaping tools 2 and 3 andat least one of the clamping plates 5 and 6 is temperature controlled,in particular thermally connected to a cooling device 16, in order toquickly cool the strip W heated in the heating station to below theshaping temperature after the shaping and to stabilize the blistersformed in the thermoshaping machine 1 between the shaping tools.

A complete cycle in the thermoshaping machine 1 during the continuousfeed of the strip W is briefly described below, with reference to FIGS.1 through 9. FIG. 1 shows the shaping tools 2 and 3 in the open positionat the upstream end position 8 at the beginning of a cycle, while theclamping plates 5 and 6 are in the closed position and advancing thestrip W as a result of the lowered upper clamping plate 5. Starting fromthis FIG. 1 position, during the acceleration synchronization zone shownin FIG. 2 the shaping tools 2 and 3 are accelerated to the speed of thestrip W, while the clamping plates 5 and 6 in the feeder 4 continue theadvancement unchanged at this speed.

FIG. 3 shows the position in which the shaping tools 2 and 3 at the endof the synchronization zone have reached the speed of the strip W ondisplacement in the direction 11 toward the downstream end position 9,so that the shaping tools 2 and 3 are shifted from the open position tothe closed position and thus become active. The clamping plates 5 and 6are likewise still active in order to achieve a switchover from usingthe plates 5 and 6 to drive the strip W to using the dies 2 and 3 todrive it without any fluctuation in the web tension.

In FIG. 4 the changeover is completed, and the shaping tools 2 and 3continue to form the blisters and take over the advancement, whereas theclapping plates 5 and 6 are open and decelerating. In FIG. 5 theclamping plates 5 and 6 have reached and stopped in their downstream endposition 10 after passing through the deceleration zone, while theshaping tools 2 and 3 continue mold and cool the strip W and alsodisplace it in the direction 11.

FIG. 6 shows the position in which the clamping plates 5 and 6 havereturned to their upstream end position 7 and are still open, whereasthe shaping tools 2 and 3 continue to feed and cool the strip W. FIG. 7shows the position in which advance once again starts to change, withthe shaping tools 2 and 3 as well as the clamping plates 5 and 6 in theclosed position.

FIG. 8 shows the displacement of the shaping tools 2 and 3 to thedownstream end position and open position after they have stopped at thedownstream end of the deceleration zone. The clamping plates 5 and 6have once again sole responsibility for advance of the workpiece W afterhaving themselves finished travel through the accelerationsynchronization zone. Last, FIG. 9 shows the shaping tools 2 and 3 atthe downstream end position 9 at the end of the deceleration zone,before the shaping tools 2 and 3 return to the upstream end position 8and start a new working cycle in the thermoshaping machine 1 for thecontinuously running strip W and the plates 5 and 6 are movingdownstream at the workpiece travel speed.

1. A shaping machine comprising: upper and lower shaping tools movablevertically between an open position spaced apart and spacedly flanking ashapable strip passing between them in a generally horizontal traveldirection and a closed position gripping the strip and also movablehorizontally parallel to the strip between an upstream tool position anda downstream tool position; upper and lower clamp plates offsethorizontally from the shaping tools and movable vertically between anopen position spaced apart and spacedly flanking the strip and a closedposition gripping the strip and also movable horizontally parallel tothe strip between an upstream clamp position and a downstream clampposition; and drive means connected to the tools and plates foralternately moving the tools and the clamp plates between their open andclosed positions and for moving the tools and plates downstream in thedirection substantially only when in the respective closed positions andfor moving the tools and plates upstream in the direction substantiallyonly when in the respective open positions.
 2. The machine defined inclaim 1 wherein the drive means alternately closes and opens the shapingtools and clamp plates so as to advance the strip continuously in thedirection.
 3. The machine defined in claim 1 wherein the drive meansshifts the shaping tools and clamping plates into the respective closedpositions after some advance downstream from the respective upstream endposition and out of the respective closed positions somewhat upstream ofthe respective downstream end positions, whereby the tools and plateshave time to accelerate to a travel speed when starting movementdownstream from the respective upstream end positions and have time todecelerate to a stop when moving into the respective downstream endpositions.
 4. The machine defined in claim 1 wherein the shaping toolshave a length parallel to the direction and engageable with the stripthat is greater than a maximum travel of the tools in the directionbetween the respective upstream and downstream positions.
 5. The machinedefined in claim 1, further comprising cooling means connected to thetools.
 6. The machine defined in claim 1, further comprising coolingmeans connected to the plates.
 7. The machine defined in claim 1 whereinthe drive mesas includes variable drives effective in the direction fordisplacing the plates and tools in the direction.
 8. The machine definedin claim 1 wherein the drive means includes fluid-powered actuatorseffective vertically for displacing the plates and tools between therespective open and closed positions.
 9. The machine defined in claim 1wherein the transport direction extends at a small acute angle to thehorizontal.